Good moods are contagious, per a new study, and so are bad ones—but depression is not. In fact, lending support to a down-in-the-dumps pal can make a real difference.

Amanda MacMillan
September 21, 2017

You can actually catch a good mood or a bad mood from your friends, according to a new study in the journal Royal Society Open Science. But that shouldn’t stop you from hanging out with pals who are down in the dumps, say the study authors: Thankfully, the effect isn’t large enough to push you into depression.

The new study adds to a growing body of research suggesting that happiness and sadness—as well as lifestyle and behavioral factors like smoking, drinking, obesity, fitness habits, and even the ability to concentrate—can spread across social networks, both online and in real life. But while many previous studies have only looked at friendship data at one point in time, this is one of the few that measured social and mood changes over time.

This method was able to show how friends actually influenced each other, and helped rule out the possibility that similarities between friends exist simply because people tend to gravitate toward and hang out with others like themselves.

The new research involved groups of junior-high and high-school students who took part in depression screenings and answered questions about their best friends, many of whom were also enrolled in the study. In total, 2,194 students were included in the analysis, which used a mathematical model to look for connections among friend networks.

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Overall, kids whose friends suffered from bad moods were more likely to report bad moods themselves—and they were less likely to have improved when they were screened again six months to a year later. When people had more happy friends, on the other hand, their moods were more likely to improve over time.

Some symptoms related to depression—like helplessness, tiredness, and loss of interest—also seemed to follow this pattern, which scientists call “social contagion.” But this isn’t something sneaky and insidious that people need to worry about, says lead author Robert Eyre, a doctoral student at the University of Warwick’s Center for Complexity Science. Rather, it’s likely just a “normal empathetic response that we’re all familiar with, and something we recognize by common sense,” he says.

In other words, when a friend is going through a rough patch, it makes sense that you’ll feel some of their pain, and it’s certainly not a reason to stay away. But the fact that these negative feelings do spread across networks does have important health implications, says Eyre.

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“The good news from our work is that following the evidence-based advice for improving mood—like exercise, sleeping well, and managing stress—can help your friends too,” he says.

The study also found that having friends who were clinically depressed did not increase participants’ risk of becoming depressed themselves. “Your friends do not put you at risk of illness,” says Eyre, “so a good course of action is simply to support them.” To boost both of your moods, he suggests doing things together that you both enjoy—and taking other friends along to further spread those good feelings, too.